Why does a spark plug fire before top dead center?
Just before top dead center (TDC) the spark plug fires to start combustion. With a rich air/fuel mixture this starts burning very rapidly and the peak firing pressure will be higher than normal and also closer to TDC. The very rapid rate of pressure rise of the uncontrolled burning mixture causes detonation.
How do you find the dead center on an engine?
Usually it can be found by looking at timing marks; but on some engines these marks may be lost or hidden. Fortunately there’s an easy way to discover top dead center without the use of any timing marks. So, Being able to accurately find Top Dead Center (TDC) is a critical step; no matter what engine you are working with.
What happens when fuel is still igniting at 900 rpm?
This would mean that the fuel is still igniting while the piston is descending in the power stroke and would result in a massive loss of power. Using an engine idling at 900 rpm further illustration, the piston is moving upward at a speed that the fuel, given the time it takes to burn completely, is ignited 1/16-inch from the top.
Where to find the top dead center on a compression stroke?
As a general reference point, or when installing a distributor, Top Dead Center (TDC) on the compression stroke is required. Usually it can be found by looking at timing marks; but on some engines these marks may be lost or hidden.
Why does my car keep retarding the spark?
Reasons a Late Model Vehicle will Retard the Spark. The computer will also retard the spark if the engine is running too hot. Excess heat, coupled with lower octane-rated fuel, will cause the engine to experience spark knock. The spark timing is automatically retarded when knock is detected.
Usually it can be found by looking at timing marks; but on some engines these marks may be lost or hidden. Fortunately there’s an easy way to discover top dead center without the use of any timing marks. So, Being able to accurately find Top Dead Center (TDC) is a critical step; no matter what engine you are working with.
As a general reference point, or when installing a distributor, Top Dead Center (TDC) on the compression stroke is required. Usually it can be found by looking at timing marks; but on some engines these marks may be lost or hidden.
Reasons a Late Model Vehicle will Retard the Spark. The computer will also retard the spark if the engine is running too hot. Excess heat, coupled with lower octane-rated fuel, will cause the engine to experience spark knock. The spark timing is automatically retarded when knock is detected.
This would mean that the fuel is still igniting while the piston is descending in the power stroke and would result in a massive loss of power. Using an engine idling at 900 rpm further illustration, the piston is moving upward at a speed that the fuel, given the time it takes to burn completely, is ignited 1/16-inch from the top.